1. Field
The present application relates to an optical module that multiplexes a plurality of optical beams.
2. Related Background Art
The wavelength division multiplexing (WDM) communication has become popular, where the WDM system multiplexes a plurality of optical beams each attributed to a wavelength specific thereto and different from others. An optical module applicable to the WDM system installs a plurality of semiconductor laser diodes (LDs) that emit optical beams each having a specific wavelength different from others. Such an optical module generally installs, in order to multiplex the plural optical beams into an optical fiber, for instance, an arrayed waveguide grating (AWG), a wavelength selective filter (WSF), and so on, therein. A prior document has disclosed techniques to multiplex several optical beams emitted from LDs. A polarization beam combiner (PBC) may combine two optical beams with wavelengths same to each other but the polarizations are different by 90°.
In the WDM communication system, two or more optical beams have wavelengths specific to respective optical beams but different from others. Accordingly, a PBC to multiplex two optical beams having wavelengths same to each other is unnecessary or inadequate to install within the WDM system. A WSF and/or an AWG are generally implemented within the WDM system. However, these optical components are inherently expensive. Moreover, a WSF has a limitation in intervals between wavelengths and a wavelength range.